Trigeminal microvascular decompression for short-lasting unilateral neuralgiform headache attacks

A significant proportion of patients with short-lasting unilateral neuralgiform headache attacks are refractory to medical treatments. Neuroimaging studies have suggested a role for ipsilateral trigeminal neurovascular conflict with morphological changes in the pathophysiology of this disorder. We present the outcome of an uncontrolled open-label prospective single-centre study conducted between 2012 and 2020, to evaluate the efficacy and safety of trigeminal microvascular decompression in refractory chronic short-lasting unilateral neuralgiform headache attacks with MRI evidence of trigeminal neurovascular conflict ipsilateral to the pain side. Primary endpoint was the proportion of patients who achieved an 'excellent response', defined as 90-100% weekly reduction in attack frequency, or 'good response', defined as a reduction in weekly headache attack frequency between 75% and 89% at final follow-up, compared to baseline. These patients were defined as responders. The study group consisted of 47 patients, of whom 31 had short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing, and 16 had short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms (25 females, mean age ± SD 55.2 years ± 14.8). Participants failed to respond or tolerate a mean of 8.1 (±2.7) preventive treatments pre-surgery. MRI of the trigeminal nerves (n = 47 patients, n = 50 symptomatic trigeminal nerves) demonstrated ipsilateral neurovascular conflict with morphological changes in 39/50 (78.0%) symptomatic nerves and without morphological changes in 11/50 (22.0%) symptomatic nerves. Postoperatively, 37/47 (78.7%) patients obtained either an excellent or a good response. Ten patients (21.3%, short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing = 7 and short-lasting unilateral neuralgiform headache attacks with cranial autonomic symptoms = 3) reported no postoperative improvement. The mean post-surgery follow-up was 57.4 ± 24.3 months (range 11-96 months). At final follow-up, 31 patients (66.0%) were excellent/good responders. Six patients experienced a recurrence of headache symptoms. There was no statistically significant difference between short-lasting unilateral neuralgiform headache attacks with conjunctival injection and tearing and short-lasting unilateral neuralgiform headache attacks in the response to surgery (P = 0.463). Responders at the last follow-up were, however, more likely to not have interictal pain (77.42% versus 22.58%, P = 0.021) and to show morphological changes on the MRI (78.38% versus 21.62%, P = 0.001). The latter outcome was confirmed in the Kaplan-Meyer analysis, where patients with no morphological changes were more likely to relapse overtime compared to those with morphological changes (P = 0.0001). All but one patient, who obtained an excellent response without relapse, discontinued their preventive medications. Twenty-two post-surgery adverse events occurred in 18 patients (46.8%) but no mortality or severe neurological deficit was seen. Trigeminal microvascular decompression may be a safe and effective long-term treatment for patients suffering short-lasting unilateral neuralgiform headache attacks with MRI evidence of neurovascular conflict with morphological changes.